1. Field of the Invention
The present invention relates to an image sensing apparatus.
2. Description of the Related Art
A multiband camera having five or more color bands is more strongly influenced by the axial chromatic aberration of an imaging lens than a normal digital camera having three, R, G, and B color bands. In a multiband camera which forms color bands using a monochrome image sensor and switchable color filters, the influence of a focus error due to the axial chromatic aberration can be avoided by focus adjustment for each band (Japanese Patent Laid-Open Nos. 2001-005046 and 2004-157059).
“The focus adjustment for each band, which can be done using a filter-switchable multiband camera” described as a related art technique, cannot be performed in a multiband camera including a single-plate image sensor with all color bands.
Further, in a multiband camera including an image sensor having five or more color bands, the number ratio among pixels is not always equal in each individual band, so the resolution of this band varies depending on the number ratio. At this time, a band with a lower pixel density has a resolution that degrades in proportion to this density, so this band has substantially no resolution information. Under such circumstances, a problem resulting from a focus error due to axial chromatic aberration with respect to a high-resolution band must be solved.